Process for producing low viscosity curable polyester resin compositions

ABSTRACT

This invention relates to a process for producing low viscosity curable polyester resin compositions, which compositions contain a mixture of (i) an unsaturated ester terminally modified with a reactive olefin such as dicyclopentadiene or other Diels-Alder adducts of cyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylated derivative thereof and (ii) a polymerizable ethylenically unsaturated monomer which serves to crosslink the unsaturated ester to a thermoset product. Fiber reinforced thermoset articles can be produced from these curable polyester resin compositions.

BRIEF SUMMARY OF THE INVENTION

1. Technical Field

This invention relates to a process for producing low viscosity curablepolyester resin compositions, which compositions contain a mixture of(i) an unsaturated ester terminally modified with a reactive olefin suchas dicyclopentadiene or other Diels-Alder adducts of cyclopentadienewith an olefinic or acetylenic hydrocarbon or alkylated derivativethereof and (ii) an copolymerizable ethylenically unsaturated monomerwhich serves to crosslink the unsaturated ester to a thermoset product.Fiber reinforced thermoset resin articles can be produced from thesecurable polyester resin compositions.

2. Background of the Invention

Unsaturated polyester resins are typically used as the resin componentin the manufacture of fiber reinforced thermoset plastics. The resinsgenerally consist of unsaturated polyesters dissolved in a polymerizableethylenically unsaturated monomer such as styrene. Typically, theseunsaturated polyesters are formed by reacting an unsaturated diacid oranhydride with a nearly equivalent amount of dihydric alcohol attemperatures above about 200° C. for several hours. Maleic anhydride isthe most common acid component utilized. The dihydric alcohols which arecommonly used include ethylene glycol, 1,2-propylene glycol, dipropyleneglycol, diethylene glycol, and the like. Modifying amounts of otherdiacids, such as phthalic acid, isophthalic acid, terephthalic acid, oradipic acid are also commonly used. Phthalic anhydride is also oftenused. Unsaturation which is provided by maleate or fumarate groupswithin the backbone of the polyester takes part in the crosslinking orcuring, of unsaturated polyester resins. These unsaturated polyesterresins are considered among the least expensive resins suitable for themanufacture of a variety of fiber reinforced products.

Much effort has recently been directed toward the development ofalternative resin systems with potentially improved economics. To be aviable alternative, such resin systems should exhibit the highlydesirable properties of conventional unsaturated polyester resins andprovide fiber reinforced thermoset articles having excellent mechanicalproperties. Modification of unsaturated polyesters with olefins such asdicyclopentadiene has been investigated as one method for reducing thecost of unsaturated polyester resin systems.

Investigators have found that incorporation of dicyclopentadiene resultsin two structurally different types of polyesters. See, for example, D.L. Nelson, Considerations: Dicyclopentadiene in Polyester Resins, 36thAnnual Conference, Reinforced Plastics/Composites Institute, The Societyof the Plastics Industry, Inc., Feb. 16-20, 1981, Session 7-E, pages1-7. One polyester type contains ester and/or ether groups resultingfrom carboxyl or hydroxyl addition to one of the dicyclopentadienedouble bonds. Such ester and/or ether addition groups have the formula##STR1## The other polyester type contains Diels-Alder reaction groupsresulting from dimer cracking and subsequent reaction of cyclopentadienewith a dieneophile such as maleic acid. Such Diels-Alder groups have theformula ##STR2## when maleic acid is the dieneophile. Combinations ofthe above groups may also be incorporated in polyesters.

U.S. Pat. Nos. 3,883,612, 3,933,757, 3,986,992, 4,035,439 and Re.29,555, all assigned to SCM Corporation, disclose thickened, low shrinkmolding compositions containing a dicyclopentadiene-modified polyesterpolymer obtained by the following steps: (1) reacting a glycol, e.g.,propylene glycol, and an unsaturated dibasic acid, e.g., maleic acid, ata temperature of about 150° C. to yield an acid terminated partialcopolymer; (2) reacting dicyclopentadiene with the partial copolymerprepared in step (1) at a temperature of about 150° C. to yield aprepolymer; (3) reacting additional glycol with the prepolymer of (2) ata temperature of about 200° C. to yield a dicyclopentadiene polyesterpolymer; and (4) adding styrene to the dicyclopentadiene polyesterpolymer. Sheet molding compounds (SMC) and bulk molding compounds (BMC)were prepared from certain of the molding compositions.

U.S. Pat. Nos. 4,233,432 and 4,246,367, both assigned to United StatesSteel Corporation, disclose dicyclopentadiene modified polyester resinsand a method for preparation thereof. The resins are prepared byreacting maleic anhydride and water with dicyclopentadiene at atemperature of about 90° C. to 150° C. to give a maleic half ester ofdicyclopentyl alcohol, and thereafter reacting a glycol, e.g., propyleneglycol, at a temperature of about 210° C. to form the resultantunsaturated polyester.

U.S. Pat. No. 4,233,413, assigned to Hitachi Chemical Company, Ltd.,discloses low shrink resin compositions containing an unsaturatedpolyester obtained by reacting dicyclopentadiene with an alpha,beta-unsaturated dibasic acid, e.g., maleic acid, or reactingdicyclopentadiene with an alpha, beta-unsaturated dibasic acidanhydride, e.g., maleic anhydride and water at 150° C. or lower to yielda partially esterified dicyclopentadiene carboxylic acid, which isfurther reacted with at least one polyhydric alcohol such as a glycol,e.g., propylene glycol, at a temperature of from 150° C.-210° C. Thispatent discloses cast articles prepared from the resin compositions.

U.S. Pat. No. 4,224,430, assigned to Hitachi Chemical Company, Ltd.,discloses high solids resin compositions containing one or moreoligomers prepared by reacting dicyclopentadiene with an alpha,beta-unsaturated hydrocarbon, e.g., maleic acid or maleic anhydride, ata temperature of from 100° C.-140° C. to yield a monobasic acid, whichis further reacted with a polyhydric alcohol, e.g., diethylene glycol,at a temperature of from 180°-220° C. Cast articles were prepared fromthe resin compositions.

U.S. Pat. Nos. 4,029,848 and 4,148,765, both assigned to Dow ChemicalCompany, disclose resin compositions containing an unsaturated polyesterobtained by reacting (1) a glycol, e.g., propylene glycol, (2) anolefinically unsaturated dicarboxylic acid or anhydride, e.g., maleicanydride, (3) a saturated dicarboxylic acid or anhydride, e.g., phthalicanhydride, and (4) dicyclopentadiene at a temperature of about 140° C.for a period of time and thereafter at a temperature of about 200° C.for an additional period of time. Glass laminates were prepared fromcertain of the resin compositions by a hand roller technique.

U.S. Pat. Nos. 3,166,434 and 3,340,327 disclose resin compositionscontaining an unsaturated polyester obtained by reacting (1) anunsaturated dicarboxylic acid containing a major molar proportion offumaric acid, (2) a glycol containing a major molar proportion ofpolyoxyalkylene glycol and (3) dicyclopentadiene at a temperature up toabout 215° C. in the absence of a catalyst (see Example 1 in bothpatents). Diels-Alder reaction products accompany thispolyesterification reaction. Coatings were prepared from certain of theresin compositions.

In the above prior art methods, dicyclopentadiene or its reactionproduct is present in the reaction mixture with an unsaturated diacid oranhydride and a dihydric alcohol at temperatures of from about 150° C.to about 220° C. At these temperatures, both reacted and unreacteddicyclopentadiene become increasingly susceptible to fragmentary sidereactions. For example, the remaining double bond in reacteddicyclopentadiene becomes increasingly susceptible to esterification andetherification reactions. Also, the formation of carbic acid canpotentially occur at these high reaction temperatures. Any unreacteddicyclopentadiene can readily undergo dimer cracking at temperaturesabove about 150° C. and thereby provide for the formation of Diels-Aldergroups which can be incorporated into the structure of the polyester.Gelation of dicyclopentadiene modified polyesters has occasionally beenobserved during polyesterification of temperatures of from 150° C. to220° C., apparently due to side reactions involving the olefin. See, forexample, Comparative Examples F and G hereinbelow. Therefore, it wouldbe highly desirable to prepare dicyclopentadiene modified polyesters bya process in which dicyclopentadiene could be selectively reacted with apolyester having terminal fumarate half ester groups at low reactiontemperatures.

It has been found as a result of this invention that dicyclopentadienecan be selectively reacted at low reaction temperatures with a polyesterhaving terminal fumarate half ester groups by utilizing a non-oxidizingacid catalyst having a non-nucleophilic anion. Dicyclopentadiene need nolonger be exposed to high reaction temperatures utilized in the priorart methods, and therefore dicyclopentadiene is significantly lesssusceptible to fragmentary side reactions. The dicyclopentadienemodified polyesters of this invention contain predominantly terminalester groups resulting from selective acid addition to one of thedicyclopentadiene double bonds. The formation of Diels-Alder reactionproducts is selectively minimized by utilizing dicyclopentadiene at lowreaction temperatures.

There appears to be no prior art directed to the addition ofdicyclopentadiene at low reaction temperatures to polyesters containingpredominantly fumarate half ester terminal groups.

The curable polyester resin compositions of this invention exhibithighly desirable properties, e.g., low viscosity, rapid cure rate,excellent moisture resistance, and the like, and also provide fiberreinforced composites having excellent mechanical properties. Thecurable resin compositions exhibit faster cure rates than the resinsystems of U.S. patent application Ser. No. 626,146, filed on an evendate herewith. Cured articles prepared from the curable resincompositions of this invention also exhibit high heat deflectiontemperatures. These low viscosity resin systems are very suitable foruse in reaction injection molding of fiber reinforced thermosetarticles. The curable resin compositions can also have utility ascoatings, sealants, adhesives and the like.

3. Disclosure of the Invention

This invention relates to a process for preparing curable polyesterresin compositions, which process comprises:

(a) contacting a molar excess of an alpha, beta unsaturated dicarboxylicacid or derivative thereof, preferably selected from maleic acid oranhydride and fumaric acid, with an organic polyol for a time and at atemperature sufficient to form a composition comprising a carboxylicacid terminated polyester having the formula: ##STR3## wherein n is anumber having an average value of about 2 to less than about 4, m is anumber equal to the free valence of R less the average value of n, theratio of n to m is greater than about 2.0, preferably at least about3.0, and R is the residuum of a polyester which contained from 2 to 4inclusive hydroxyl groups;

(b) contacting a Diels-Alder adduct of cyclopentadiene with an olefinicor acetylenic hydrocarbon or alkylated derivative thereof with thecarboxylic acid terminated polyester of (a) in the presence of anon-oxidizing acid catalyst having a non-nucleophilic anion for a longtime and at a temperature sufficient to form a composition comprising anunsaturated ester having the formula: ##STR4## wherein n, m and R are asdefined above and R₁ is the residuum of a Diels-Alder adduct ofcyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylatedderivative thereof having from 2 to about 20 carbon atoms; and

(c) admixing a copolymerizable ethylenically unsaturated monomer withthe unsaturated ester of (b).

The unfilled curable polyester resin compositions prepared by theprocess of this invention have a low viscosity, i.e., from about 10 toabout 1500 centipoises, preferably less than about 1000 centipoises, andmost preferably less than about 600 centipoises, so that they can beused to produce thermoset resin articles containing up to about 75weight percent of reinforcing fibers by a rapid injection moldingprocess. A low viscosity curable molding composition is highly desirablein a rapid injection molding process in order to avoid any movement ofthe reinforcing fibers during the injection step. Composite articles canbe produced from the curable molding compositions of this invention by arapid injection molding process which is typically less than threeminutes, oftentimes less than two minutes, from the time the cure of theresin mixture is initiated. Other composite fabrication processes suchas spray up, wet lay up, resin transfer molding, centrifugal casting andfilament winding can also utilize the resin compositions of thisinvention. The resin compositions can also be used in sheet moldingcompound (SMC) and bulk molding compound (BMC).

The fiber reinforced thermoset resin articles prepared from the curablemolding compositions have utility in many end-use applications such asautomobile parts, appliance housings, and the like.

Process step (b) of this invention in which dicyclopentadiene isselectively added to the carboxylic acid terminated polyester is carriedout at a temperature below 150° C. Dicyclopentadiene is therefore notexposed to high reaction temperatures. No volatile byproducts are formedduring this process which is an economically attractive feature.Dicyclopentadiene modified polyesters prepared by the process of thisinvention have a comparatively narrow molecular weight distributions asdetermined by conventional analytical techniques such as gel permeationchromatography. The dicyclopentadiene modified polyesters containpredominantly terminal ester groups resulting from selective addition ofcarboxyl groups to one of the dicyclopentadiene double bonds. Theformation of Diels-Alder reaction products such as carbic anhydride orcarbic acid is selectively minimized by utilizing dicyclopentadiene atlow reaction temperatures. In addition to their utility as matrix resinsof fiber reinforced thermoset articles, such resin compositions can haveutility as coatings intermediates, sealants, adhesives and the like.

DETAILED DESCRIPTION

The process for preparing the curable polyester resin compositions whichare suitable for use in the fabrication of fiber reinforced thermosetarticles involves the following general steps:

(1) preparation of a carboxylic acid terminated unsaturated polyesterhaving predominantly terminal fumarate half ester groups by reacting amolar excess of an alpha, beta unsaturated dicarboxylic acid orderivative thereof selected from maleic acid or anhydride and fumaricacid with an organic polyol;

(2) addition of a non-oxidizing acid catalyst having a non-nucleophilicanion;

(3) preparation of an unsaturated ester by selectively reacting aDiels-Alder adduct of cyclopentadiene with an olefinic or acetylenichydrocarbon or alkylated derivative thereof such as dicyclopentadienewith terminal carboxylic acid groups of the unsaturated polyester ofstep (1); and

(4) Addition of an ethylenically unsaturated monomer such as styrene.

Process step (3) of this invention in which dicyclopentadiene isselectively added to the carboxylic acid terminated polyester is carriedout at a temperature below 150° C. Dicyclopentadiene is therefore notexposed to high reaction temperatures. No volatile byproducts are formedduring this process which is an economically attractive feature. Thedicyclopentadiene modified polyesters contain predominantly terminalester groups resulting from selective carboxyl addition to one of thedicyclopentadiene double bonds. The formation of Diels-Alder reactionproducts such as carbic anhydride or carbic acid is selectivelyminimized by utilizing dicyclopentadiene at low reaction temperatures.The curable polyester rein compositions prepared by the process of thisinvention are particularly suitable for the rapid fabrication of fiberreinforced thermoset articles.

The carboxylic acid terminated unsaturated polyester prepared in step(1) can be characterized by the following empirical formula: ##STR5##wherein n is a number having an average value of about 2 to less thanabout 4, m is a number equal to the free valence of R less the averagevalue of n, the ratio of n to m is greater than about 2.0, preferably atleast about 3.0, and R is the residuum of a polyester which containedfrom 2 to 4 inclusive hydroxyl groups. Since low molecular weightpolyesters are preferred, a molar excess of alpha, beta unsaturateddicarboxylic acid or derivative thereof is employed in the process. Themolar excess is between about 5 and 60 percent, preferably between about15 and 50 percent.

The temperature utilized in step (1) can range from about 150° C. toabout 240° C., preferably from about 170° C. to about 220° C. Thereaction time for step (1) can range from about 1 hour or less to about20 hours or longer. The only requirement is that the alpha, betaethylenically unsaturated dicarboxylic acid or derivative thereof andthe organic polyol react for a time and at a temperature sufficient toform the carboxylic acid terminated unsaturated polyester havingpredominantly terminal fumarate half ester groups.

The alpha, beta unsaturated dicarboxylic acids or derivatives thereofwhich can suitably be employed in step (1) above include maleic acid andanhydride and fumaric acid. Modifying amounts of other acids oranhydrides not containing reactive carbon-carbon double bonds such asortho-phthalic acid and anhydride, isophthalic acid, terephthalic acid,and adipic acid may also be used. A molar excess of alpha, betaunsaturated dicarboxylic acid or anhydride is employed in step (1) toprovide a polyester composition having predominantly terminal fumaratehalf ester groups. Typical polyesters contain at least 75 mole percentof terminal carboxylic acid groups.

The R group in the carboxylic acid terminated unsaturated polyesterdepicted by empirical formula (I) is derived from a polyester having anumber average molecular weight not exceeding 3000 and is obtained bythe condensation of a diol with an dicarboxylic acid or anhydride, ormixtures of diols and diacids. Isomerization of the meleate to fumarateconfiguration occurs simultaneously with polyesterification. Thepolyester is typically prepared at temperatures of about 200° C. fromdiols such as 1,2-propylene glycol, ethylene glycol, 1,3-butanediol,2,2-dimethyl-1,3-propanediol, dipropylene glycol, diethylene glycol,2,2-dimethyl-3-hydroxypropyl 2,2-dimethyl-3-hydroxypropionate,1,4-cyclohexane dimethanol, trimethylolpropane, polycaprolactone estersof trimethylolpropane or 1,4-butanediol,2,2-bis(4-hydroxy-phenyl)propane, the ethylene and propylene oxideadducts of 2,2-bis(4-hydroxypropyl)propane, and mixtures thereof, and amolar excess of dicarboxylic acids or anhydrides, such as maleic acidand anhydride, orthophthalic acid and anhydride, isophthalic acid,terephthalic acid, fumaric acid, carbic acid and anhydride, and mixturesthereof. Preferably at least 80 weight percent of the acid component isan alpha, beta-unsaturated dicarboxylic acid.

Carbic acid is bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid and carbicanhydride is bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid anhydride.

Modifying amounts of trifunctional acids, such as trimellitic acid;linear saturated diacids, such as adipic acid; or triols, such astrimethylol propane may also be used. Typical polyesters have acidnumbers of 100 to 300 mg KOH/gm.

The catalyst added to the reaction mixture in step (2) above is anon-oxidizing acid catalyst having a non-nucleophilic anion. Thiscatalyst is essential for effecting the selective addition of a reactiveolefin such as dicyclopentadiene or other Diels-Alder adducts ofcyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylatedderivative thereof to the carboxylic acid terminated unsaturatedpolyester prepared in step (1) having predominantly terminal fumarateester groups. A non-oxidizing acid catalyst having a non-nucleophilicanion is defined herein to mean that (1) a 10 percent by weight watersolution has a pH of less than 1.0 and (2) the anion portion of the aciddoes not easily participate in a displacement reaction with organichalides.

Suitable non-oxidizing acid catalysts having a non-nucleophilic anioninclude fluoroboric acid, trifluomethanesulfonic acid (triflic acid),hexafluorophosphoric acid, hexafluoroantimonic acid, and the like.Supported acid catalysts such as Nafion resins may also be used in thisinvention. The preferred non-oxidizing acid catalyst having anon-nucleophilic anion is fluoroboric acid. Such catalysts are generallyemployed in an amount of from about 0.01 weight percent to about 4.0weight percent, preferably from about 0.05 weight percent to about 2.0weight percent, based on the total weight of the carboxylic acidterminated unsaturated polyester. These catalysts do not adverselyaffect cure of the polyester rein systems of this invention.

Acid or acid acting catalytic materials such as sulphuric acid, zincchloride or p-toluenesulfonic acid are not suitable for effecting theselective, rapid addition of dicyclopentadiene to the carboxylic acidterminated unsaturated polyesters prepared in step (1).

The unsaturated ester prepared in step (3) above can be characterized bythe following empirical formula: ##STR6## wherein n, m and R are asdefined above and R₁ is the residuum of a Diels-Alder adduct ofcyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylatedderivative thereof having from 2 to about 20 carbon atoms. Suitableolefinic hydrocarbons include ethylene, butadiene, cyclopentadiene,alkylated cyclopentadiene and the like. Suitable acetylenic hydrocarbonsinclude acetylene, 1-hexyne, 2-butyne, 1-butyne, phenylacetylene and thelike. R₁ is preferably derived from dicyclopentadiene. However, otherDiels-Alder adducts of cyclopentadiene such as methyl dicyclopentadiene,norbornene and norbornadiene may also be used to selectively modify thecarboxylic acid terminated unsaturated polyester prepared in step (1).

The dicyclopentadiene useful in this invention is a commercialconcentrate product generally prepared by dimerizing a crude C₅ streamderived from the cracking of crude mixtures of hydrocarbons as set forthin U.S. Pat. No. 3,557,239. Such commercial concentrate products includeDicyclopentadiene 97 commercially available from Exxon Chemical Company,Houston, Tex., and resin grade C₁₀ concentrate commercially availablefrom Dow Chemical Company, Midland, Mich.

The commercial dicyclopentadiene concentrates generally contain fromabout 60 to about 97 percent by weight of dicyclopentadiene, about 5 to30 weight percent of the mixed Diels-Alder dimers of diolefins such asbutadiene, cyclopentadiene, isoprene, cis and trans piperylene andmethyl cyclopentadiene. Any remaining amounts in these concentratesgenerally contain benzene, cyclopentene, 1,5-hexadiene and oligomers ofthe above diolefins.

The Diels-Alder adducts of cyclopentadiene with an olefinic oracetylenic hydrocarbon or alkylated derivative thereof, e.g.,dicyclopentadiene, can be incorporated into the carboxylic acidterminated unsaturated polyester by two methods, i.e., via an additionreaction ##STR7## or by a Diels-Alder reaction ##STR8## The Diels-Alderreaction may also occur between the internal unsaturation in the polymerchain and cyclopentadiene. The properties of the resin compositionsdepend critically on how dicyclopentadiene is incorporated. In theprocess of this invention, conditions are tailored to favor the additionreaction. The formation of Diels-Alder reaction products such as carbicanhydride or carbic acid is selectively minimized by utilizingdicyclopentadiene at the low reaction temperatures employed in theprocess of this invention. For applications where fast cure is importantsuch as in automotive applications, it is preferable to incorporatedicyclopentadiene via the addition mode. The addition mode is alsopreferred for improved compatibility of the polyester compositions withethylenically unsaturated monomers such as styrene and for reducedmoisture sensitivity in cured resins prepared therefrom.

The preferred stoichiometry is 0.7 to 1.2 moles of the Diels-Alderadduct of cyclopentadiene with an olefinic or acetylenic hydrocarbon oralkylated derivative thereof, e.g., dicyclopentadiene, per one mole ofcarboxylic group in the unsaturated polyester prepared in step (1).Since some of the dicyclopentadiene condenses with itself, molar ratiosslightly above 1.0 can be employed without difficulty if desired. Theunsaturated esters prepared in step (3) have acid numbers of about 70 mgKOH per gram of unsaturated ester or less.

The temperature utilized in the reaction of step (3) can range fromabout 80° C. to about 140° C., preferably from about 100° C. to about130° C. Since dicyclopentadiene is thermally unstable above about 150°C., it is necessary to cool the reaction mixture below that temperatureprior to the addition thereof. In this manner, the amount ofdicyclopentadiene incorporated via the "addition mode" is maximized andvery little, if any, Diels-Alder addition takes place. The reaction timefor step (3) can vary from about 0.1 hours or less to about 5 hours orlonger. The only requirement is that the dicyclopentadiene react withthe carboxylic acid terminated unsaturated polyester in the presence ofthe non-oxidizing acid catalyst having a non-nucleophilic anion for atime and at a temperature sufficient to form the unsaturated esterdepicted in empirical formula (II) above. Since the addition ofdicyclopentadiene to the fumarate half ester groups of the carboxylicacid terminated unsaturated polyester is an exothermic reaction, it isdesirable to add the dicyclopentadiene at such a rate that the reactiontemperature remains below about 130° C. An inert solvent may be employedfor this step if desired. In the absence of the non-oxidizing acidcatalyst having a non-nucleophilic anion in step (2) above, mixtures ofcarboxylic acid terminated unsaturated polyesters having predominantlyterminal fumarate half ester groups and dicyclopentadiene are unreactiveat a temperature of 120° C.

Suitable ethylenically unsaturated monomers which can be employed instep (4) above include one or more ethylenically unsaturatedcopolymerizable monomers which are soluble in and copolymerizable withthe unsaturated ester prepared in step (3). Typically, the ethylenicallyunsaturated monomer is added to the reaction mixture after all of theolefinic compound, e.g., dicyclopentadiene, has reacted in step (3).These ethylenically unsaturated monomers contain at least a single--CH═C< group, and preferably a CH₂ ═C< group and include styrene andits derivatives and homologues, diallyl phthalate, triallylisocyanurate, nonfunctionalized esters of acrylic or methacrylic acid(such as ethyl acrylate, butyl acrylate, and methyl methacrylate),unsaturated nitriles (such as acrylonitrile and methacrylonitrile) andthe like. Also included herein are low levels of maleic anhydride.

Other suitable ethylenically unsaturated monomers include acrylic ormethacrylic acid or a functionalized derivative thereof having amolecular weight of less than 300. Mixtures of these may also be used inthis invention. The functionalized derivatives are characterized by thepresence of acrylate, methacrylate, acrylamide, and methacrylamidegroups and also by the presence of functional groups such as hydroxyl,amino, alkylamino, and epoxide, for example. The molecular weight ofthese monomers is typically less than 300. Preferred monomers arecharacterized by the following formula: ##STR9## wherein R₂ isindependently hydrogen or methyl; X and Y are independently --O-- or##STR10## wherein R₅ is hydrogen or lower alkyl; R₃ is an aliphatic oraromatic radical containing from 2 to about 10 carbon atoms, optionallycontaining --O-- or ##STR11## R₄ is hydrogen or an aliphatic or aromaticradical containing from 1 to 10 carbon atoms; and p and q are integersof or greater than 1, preferably 1 to 3.

These functionalized derivatives of acrylic or methacrylic acid include2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxylpropylacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate,hydroxybutyl methacrylate, 2-aminoethyl acrylate, 2-aminoethylmethacrylate, 2-methylaminoethyl acrylate, 2-methylaminoethylmethacrylate, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethylmethacrylate, 2-hydroxyethyl acrylamide, 2-hydroxyethyl methacrylamide,2-aminoethyl acrylamide, 2-aminoethyl methacrylamide, diethylene glycolmonoacrylate, diethylene glycol monomethacrylate, 2-methoxyethylacrylate, 2-methoxyethyl methacrylate, pentaerythritol monoacrylate,pentaerythritol monomethacrylate, pentaerythritol diacrylate,pentaerythritol dimethacrylate, pentaerythritol triacrylate, glycerolmonoacrylate, glycerol monomethacrylate, trimethylolpropanemonoacrylate, trimethylolpropane monomethacrylate, glycidylmethacrylate, glycidyl acrylate, hydroxymethyl acrylamide and the likeor mixtures thereof. It is understood that several isomers of many ofthese monomers exist and would be suitable for use herein either asindividual components or as mixtures with any of the other monomers.Similarly, it is understood that additional derivatives containingaromatic rings and other alkyl groups in the acid or ester portion ofthe above formula may also be included.

Preferred functionalized derivatives of acrylic or methacrylic acidemployed in the practice of this invention include 2-hydroxyethylmethacrylate, 2-hydroxyethyl acrylate, hydroxypropryl acrylate andhydroxypropyl methacrylate.

Mixtures of the aforementioned ethylenically unsaturated monomers may beeffectively employed in the practice of this invention.

The preferred ethylenically unsaturated monomer contemplated in thepractice of this invention is styrene or a mixture of styrene and2-hydroxyethyl methacrylate.

The ethylenically unsaturated monomer is present in the curable resincompositions in an amount of from about 10 to about 75 weight percent,preferably from about 25 to about 65 weight percent. The unsaturatedester prepared in step (3) is present in the curable resin compositionsin an amount from about 25 to about 90 weight percent, preferably fromabout 35 to about 75 weight percent.

Although the process for preparing the curable resin compositionsproduces no volatiles, a small amount of solid precipitate usuallyforms. This solid amounts to less than about 3 weight percent of thetotal resin composition weight, and consists primarily of fumaric acidwhich is a by-product of step (1). The solid can be removed bycentrifugation or filtration.

The curable resin compositions may also be treated with a weak baseprior to curing. Treatment with a weak base minimizes discolorationcaused by high temperatures during cure, especially whenhexafluorophosphoric acid or trifluoromethanesulfonic acid (triflicacid) are used as catalysts for the addition of the Diels-Alder adductof cyclopentadiene with an olefinic or acetylenic hydrocarbon oralkylated derivative thereof, e.g., dicyclopentadiene, to the carboxylicacid terminated unsaturated polyester in step (3). Suitable weak basesinclude crosslinked polyvinylpyridine, disodium acid phosphate, sodiumcarbonate, alumina and the like. When using sodium carbonate in the weakbase treatment step, a desiccant such as magnesium sulfate is also addedto scavenge water generated in the neutralization process. The weak basecan be employed in an amount of from about 0.1 weight percent to about10.0 weight percent, preferably from about 0.2 weight percent to about5.0 weight percent, based on the total weight of the resin composition.Preferably the weak base is separated from the resin by, for example,filtration before the resin is molded.

It is furthermore desirable to utilize a vinyl polymerization inhibitorin those cases where the curable polyester resin composition is to bestored and/or shipped. Suitable vinyl polymerization inhibitors arehydroquinone, para-benzoquinone, phenothiazine, 4-nitrophenol, t-butylcatechol, quinhydrone, toluhydroquinone, mono-t-butyl hydroquinone,2,5-di-t-butylhydroquinone, hydroquinone monomethyl ether, the biphenolderivatives described in U.S. Pat. No. 4,158,027, and the like. Theamount of inhibitor for the purpose of preventing vinyl polymerizationcan be that conventionally used, namely, from about 100 to about 1000ppm of the total weight of the resin composition.

A free radical initiator which initiates curing via the co-reaction ofthe unsaturated ester and the ethylenically unsaturated monomer can alsobe included in the curable polyester resin compositions of thisinvention. These initiators include azo compounds, peroxides, peresters,perketals, and the like including mixtures thereof.

Azo and peroxide initiators are described by, for example, Gallagher etal. "Organic Peroxides Review, Plastics Design and Processing", July1978, pages 38-42, and August 1978, pages 60-67 inclusive. Thetechnology disclosed in those two articles is incorporated herein byreference. The choice of the specific peroxide or azo initiators ormixtures thereof for the purpose of curing the molding compositions ofthis invention is within the purview of those having skill in this artand the manner in which such peroxides and azo initiators effect adesirable cure is generally characterized in the aforementionedarticles.

Examples of such initiators include 1,1-di-t-butyl-peroxycyclohexane,1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane,2,2-di-t-butylperoxybutane, 2,2-di-t-butyl-peroxy-4-methyl-pentane,2,2-dicumylperoxypropane, butyl 2,2-di-t-butylperoxyvalerate,2,2'-azo-bisisobutyronitrile, benzoyl peroxide, lauroyl peroxide,di-t-butyl peroxide, t-butyl-perpivalate,2,5-dimethylhexane-2,5-di-perethylhexanoate, t-butyl peroctoate, t-butylperneodecanoate, t-butyl perbenzoate, t-butyl percrotonate, t-butylperisobutyrate, di-t-butyl perphthalate,bis(4-t-buty-cyclohexyl)peroxydicarbonate, methyl ethyl ketone peroxide,2,4-pentanedione peroxide, ethyl 3,3-di(butylperoxy)butyrate, and thelike.

The peresters and perketals may be used in combination with an acid cureaccelerator as described in Netherlands published Patent Application No.7604405. These acids include Bronsted acids with a pK_(a) value lowerthan or equal to that of formic acid, such as hydrochloric acid,sulfuric acid, nitric acid, phosphoric acid, trichloroacetic acid,p-toluenesulfonic acid, and the like. Also, Lewis acids or metal halideswith Lewis acid properties, such as boron trifluoride and the chloridesof iron, cobalt, zinc and aluminum, may be used.

Additionally, the above described initiators may be used in combinationwith other cure accelerators such as cobalt compounds. These cobaltcompounds include cobalt naphthenate, cobalt-amine cure promoters (suchas those designated as PEP 183-S and available from Air ProductsIncorporated), and the like. These cure accelerators operate bydecomposing the curing catalysts at a temperature below their normalactivation or decomposition temperature.

Mixtures of free radical initiators may be used advantageously herein,such as mixtures of peresters and/or perketals, of perketals and azocompounds, of peresters and axo compounds, or of an azo compound and aperoxide containing compound.

For coating compositions, a preferred initiator package includes methylethyl ketone peroxide and cobalt octoate.

Curing can also be effected by photopolymerization of coatingscontaining the resin compositions of this invention and aphotoinitiator. Curing occurs on exposure of such resin compositions toany source of radiation emitting actinic radiation at a wavelengthwithin the ultraviolet and visible spectural regions. Suitable sourcesof radiation include mercury, xenon, carbon arc and tungsten filamentlamps, sunlight, etc. Exposures may be from less than about 1 second to10 minutes or more depending upon the amounts of particularpolymerizable materials and photoinitiators being utilized and dependingupon the radiation source and distance from the source and the thicknessof the coating to be cured. The compositions may also be polymerized byexposure to electron beam irradiation.

The concentration of the initiator or initiator mixture can be variedwithin wide limits. As a representative range, the concentration canvary from about 0.25 to about 3.0 weight percent, preferably from about0.5 to about 2.5 weight percent, and most preferably, from about 0.60 toabout 2.0 weight percent, based on the weight of the resin composition.

The curable polyester resin compositions of this invention may alsocontain one or more of the known types of conventional additives, whichare employed for their known purposes in the usual amounts. Illustrativeof such additives are mold release agents or lubricants, pigments,fillers such as clay, hydrated alumina, silica, calcium carbonate andothers known to the art, thermoplastic polymers, other thermosettingcomponents such as epoxies, viscosity reducing agents, and the like.These additives can be dissolved or dispersed in the curable resincompositions to form a uniform mixture.

The fibers suitable for use in this invention as reinforcing agents havea melting point or a glass transition temperature above about 130° C.These fibers include fiberglass, carbon fibers, aromatic polyamidefibers (such as aramid fibers sold by E. I. duPont de Nemours Company,Wilmington, Del., under the trademark of Kevlar), metal fibers, such asaluminum and steel fibers, boron fibers, and the like. The carbon fibersinclude those having a high Young's modulus of elasticity and hightensile strength. The carbon fibers may be produced from rayon,polyacrylonitrile or petroleum pitch. Preferred fiber lengths are 1 ormore inches. Continuous filaments may also be used. It is also withinthe scope of this invention to include the use of fiber reinforcementsof shorter lengths and also fillers such as milled glass.

The preferred fibers are fiberglass, carbon fibers, aromatic polyamidefibers, and mixtures thereof. The molded article contains from about 10to about 75 weight percent, preferably from about 15 to about 65 weightpercent of the reinforcing fiber.

The curable polyester resin compositions of this invention are preparedby solution blending the unsaturated ester material, the ethylenicallyunsaturated monomer and any other optional ingredients such as afree-radical curing agent at ambient temperature. Insoluble additivessuch as calcium carbonate filler can be effectively dispersed in thecurable molding compositions. This mixture constitutes the "resinportion" which is a term used herein.

The fiber reinforced molded articles of this invention may be preparedby injecting the resin portion into a bed of one or more of the fibers.After the resin cures, the resulting composite possesses high stiffnessand strength.

A preferred process for the rapid fabrication of a fiber reinforcedmolded article from the curable resin compositions of this invention isdescribed in U.S. patent application Ser. No. 135,906 entitled "MoldingProcess and Apparatus Therefore," and filed on Apr. 14, 1980 in the nameof R. Angell, Jr., which is incorporated herein by reference. In saidprocess, the fiber reinforcement is comprised of one or more fibers witha melting point or a glass transition temperature above about 130° C.The process comprises the steps of (a) providing in a heatable matchedmetal die mold, a bonded web of one or more of said fibers, (b)providing in an accumulator zone, a liquid body of a thermosettableorganic material which is curable upon heating to a thermoset resincomposition, the viscosity of said liquid body being maintainedessentially constant in the accumulator zone by keeping its temperaturebelow that at which curing of said materials is substantial, (c) closingsaid mold containing said web, (d) injecting at least a portion of saidthermosettable organic material under pressure from said accumulatorzone into the mold to thereby fill the cavity in said mold, (e)initiating the curing of said materials by subjecting the materials to atemperature by heating the mold, which is above the temperature at whichthe curing of said materials is initiated, and (f) opening said mold andremoving the cured thermoset article therefrom.

An important aspect of the present invention is that when the curableresin compositions are injected into the interior of the mold, thefibers are not displaced or at most, only slightly displaced from theiroriginal position. As a result, the positioning of the fiberreinforcement within the framework of the molded article can thereforebe predetermined and maintained in the final molded product. This allowsone to achieve a molded product having high and predictable mechanicalproperties. These properties are determined by the original fiberplacement in the mold and are not affected by additional fiber movementwhen the resin system is injected.

In order to prevent or reduce fiber displacement (i.e., movement and/ororientation) during resin injection, the curable polyester resincompositions of this invention have a viscosity of from about 10 toabout 1500 centipoises, preferably less than about 1000 centipoises, andmost preferably less than about 600 centipoises. Curable resincompositions having viscosities higher than about 1500 centipoisesgenerally cause substantial fiber movement in the resulting composites.Such composites having non-uniform fiber distribution exhibit poormechanical properties.

A preferred apparatus for use in preparing fiber reinforced moldedarticles from curable resin compositions in accordance with thisinvention is also described in U.S. patent application Ser. No. 135,906,filed Apr. 14, 1980. The apparatus is described as comprising: (a) aheatable matched metal die mold containing one or more cavities thereinwith means for opening said mold to expose such cavities, and closingthe same, and means for controlling the injection of a thermosettableorganic liquid to such cavities when the mold is closed, (b) meansassociated with said mold, whereby one or more fibers in the form of aninterlocked mass are provided in a portion of the cavities thereof whenthe mold is open to expose such cavities and prior to the injection ofthe thermosettable organic liquid to such cavities when the mold isclosed, (c) accumulator means associated with said mold which cancontain a thermosettable liquid transportable to means for controllinginjection of said liquid to such cavities, and (d) cooling meansassociated with the means for controlling the injection of such liquidto such cavities, whereby the temperature of the liquid in suchinjection means is maintained substantially below the temperature of themold.

Although this invention has been described with respect to a number ofdetails, it is not intended that this invention should be limitedthereby. The examples which follow are intended solely to illustrate theembodiments of this invention which to date have been determined and arenot intended in any way to limit the scope and intent of this invention.

The resin compositions, non-reinforced castings and cured glassreinforced composites prepared in the examples hereinbelow wereevaluated according to the following procedures:

Proton nuclear magnetic spectroscopy was used to determine the relativeamounts of maleates, i.e., maleic acid, maleic anhydride, maleate halfester and maleate diester, and the amounts of fumarates, i.e., fumaricacid, fumarate half ester and fumarate diester, in the polyestercompositions. In general, a sample was dissolved in d₆ -dimethylsulfoxide and the areas for the resonances from the vinylic protons,i.e., --CH═CH--, were compared against each other. The resonance for thevinylic protons in maleic anhydride appeared at approximately δ=7.4 ppmrelative to the protons in tetramethylsilane, the internal standard.Resonances for these protons in fumarates appeared at approximatelyδ=6.8 ppm relative to the internal standard, and resonances for theseprotons in maleates, i.e., maleic acid, maleate half ester and maleatediester, appeared at approximately δ=6.25 ppm.

Acid Number: A resin sample weighed to the nearest 0.01 gram was addedto a flask containing 50 milliliters of a mixture of pyridine andmethanol (1:1 volume ratio). The contents in the flask were titratedwith 0.5 N aqueous potassium hydroxide using phenolphthalein as an endpoint indicator. The acid number was calculated as follows: ##EQU1##where A is the milliliters of potassium hydroxide titration solutionrequired for the resin sample and N is the normality of the potassiumhydroxide solution.

Viscosity: A resin sample was equilibrated at 25° C. and the viscositywas determined using a Brookfield model LVT viscometer.

SPI Gel Time: The cure characteristics of the resin compositions weremonitored by the procedure described in A. L. Smith, 6th SPI, Chicago,Ill., 1951, Reinforced Plastics Div., Section 1, page 1.

Flexural Strength: ASTM D-790.

Flexural Modulus: ASTM D-790.

Heat Deflection Temperature: ASTM D-648.

Tensile Strength: ASTM D-638.

Tensile Modulus: ASTM D-638.

Elongation: ASTM D-638.

Barcol Hardness: measured using a Barcol Model 934 Impressor from BarberColeman Company, Rockford, Ill.

Glass content was determined by ashing.

Unless otherwise indicated, the examples hereinbelow utilized highpurity dicyclopentadiene commercially available from Exxon ChemicalCompany, Houston, Tex. as Dicyclopentadiene 97.

Examples 1 through 7 describe the preparation of the resin compositionsof this invention.

EXAMPLE 1

Into a 5 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added 1569 grams (16.0moles) of molten maleic anhydride, 457 grams (6.0 moles) of propyleneglycol, 637 grams (6.0 moles) of diethylene glycol and 150 millilitersof xylene. The resulting reaction mixture was heated to a temperature of206° C. with continuous stirring over a 5 hour period. Water wascollected in the distillate receiver during this period. The reactionmixture was then maintained at a temperature of from 200° C. to 206° C.for a period of 3.5 hours, and an additional amount of water wascollected in the distillate receiver. The reaction mixture was thencooled to a temperature of 155° C., and thereafter subjected to a vacuumof about 27 inches of mercury for a period of one hour to remove anyresidual water and xylene. A nitrogen blanket was maintained throughoutthe entire reaction period. Titrimetric analysis indicated that theresulting reaction mixture had an acid number of 165 mg KOH/gram inpyridine/methanol. The high acid number indicated that the reactionmixture consisted predominantly of a carboxyl-terminated unsaturatedpolyester. NMR spectroscopic analysis revealed that the carbon-carbondouble bonds in maleate form (cis) were isomerized to the fumarate form(trans) in the carboxyl-terminated unsaturated polyester during thecondensation reaction.

To a 1510 gram portion of the reaction mixture prepared above containingpredominantly the carboxyl-terminated unsaturated polyester, whichportion had been cooled to a temperature of 120° C., was added 0.8 gramsof methylhydroquinone and 3.0 milliliters of fluoroboric acid (a 48weight percent solution in water). Thereafter, for a period of 75minutes, 587 grams (4.44 moles) of dicyclopentadiene were added slowlyinto the reaction flask with continuous rapid stirring at a temperatureof from 120° C. to 126° C. The reaction mixture was then maintained at atemperature of 120° C. for a period of one hour with continuousstirring. The extent of the reaction between dicyclopentadiene and thecarboxyl-terminated unsaturated polyester was monitored by titration forresidual acid, and also by NMR spectroscopy.

Following the one hour heating period, 953 grams of styrene containing0.8 grams of methylhydroquinone were added into the reaction flask withcontinuous rapid stirring. The resulting mixture was cooled to ambienttemperature and filtered to give a filtrate product and a small amountof a solid by-product. NMR spectroscopic analysis indicated that thesolid by-product consisted predominantly of fumaric acid. The filtrateproduct was a clear brown fluid which weighed 3003 grams. NMRspectroscopic analysis indicated that the product prior to styreneaddition consisted predominantly of a dicyclopentadiene-terminatedunsaturated polyester.

EXAMPLE 2

Into a 5 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added 1569 grams (16.0moles) of molten maleic anhydride, 913 grams (12.0 moles) of propyleneglycol and 150 milliliters of xylene, The resulting reaction mixture washeated to a temperature of 190° C. with continuous stirring over a 3hour period. After 40 minutes into the 3 hour period, the reactionmixture had reached a temperature of 165° C. and the first drop ofdistillate (water) appeared in the receiver. At the end of the 3 hourperiod, the reaction mixture had reached a temperature of 190° C. and 72milliliters of water had been collected in the receiver. The reactionmixture was then maintained at a temperature of from 190° C. to 214° C.for a period of 8 hours. At the end of this 8 hour period, 130milliliters of water had been collected in the receiver. The reactionmixture was then cooled to a temperature of 150° C., and thereaftersubjected to a vacuum of about 27 inches of mercury for a period of 30minutes to remove any residual water and xylene. A nitrogen blanket wasmaintained throughout the entire reaction period. Titrimetric analysisindicated that the resulting yellow hazy reaction mixture had an acidnumber of 207 mg KOH/gram in pyridine/methanol. The high acid numberindicated that the reaction mixture consisted predominantly of acarboxyl-terminated unsaturated polyester. NMR spectroscopic analysisrevealed that the carbon-carbon double bonds in maleate form (cis) wereisomerized to the fumarate form (trans) in the carboxyl-terminatedunsaturated polyester during the condensation reaction.

To a 1008 gram portion of the reaction mixture prepared above containingpredominantly the carboxyl-terminated unsaturated polyester, whichportion had been cooled to a temperature of 120° C., was added 0.3 gramsof methylhydroquinone and 2.3 milliliters of fluoroboric acid (a 48weight percent solution in water). Thereafter, for a period of one hour,492 grams (3.72 moles) of dicyclopentadiene were added slowly into thereaction flask with continuous rapid stirring at a temperature of from105° C. to 125° C. The reaction mixture was then maintained at atemperature of 115° C. for a period of one hour with continuousstirring. The extent of the reaction between dicyclopentadiene and thecarboxyl-terminated unsaturated polyester was monitored by titration forresidual acid, and also by NMR spectroscopy.

Following the one hour heating period, 1000 grams of styrene containing0.9 grams of methylhydroquinone were added into the reaction flask withcontinuous rapid stirring. The resulting mixture was cooled to ambienttemperature and filtered to give a filtrate product and a small amountof a solid by-product. NMR spectroscopic analysis indicated that thesolid by-product consisted predominantly of fumaric acid. The filtrateproduct was a clear brown fluid. A portion of the filtrate product wasdiluted with styrene to produce a solution containing 45 weight percentof styrene. The solution had a viscosity of 82 centipoises at 25° C. andan acid number of 10 mg KOH/gram in pyridine/methanol. The low acidnumber indicated that the filtrate product consisted predominantly of adicyclopentadiene-terminated unsaturated polyester. NMR spectroscopicanalysis indicated that the product prior to styrene addition consistedpredominantly of a dicyclopentadiene-terminated unsaturated polyester.

EXAMPLE 3

Into a 3 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added 588 grams (6.0moles) of molten maleic anhydride, 248 grams (4.0 moles) of ethyleneglycol and 50 milliliters of xylene, The resulting reaction mixture washeated to a temperature of 200° C. with continuous stirring over a 4hour period. Water was collected in the distillate receiver during thisperiod. The reaction mixture was then maintained at a temperature of200° C. for a period of 3 hours. At the end of this 3 hour period, about30 milliliters of water had been collected in the receiver. The reactionmixture was then cooled to a temperature of 150° C., and the appearancethereof changed from a clear yellow solution to a cream-colored fluid. Anitrogen blanket was maintained throughout the entire reaction period.Titrimetric analysis indicated that the cream-colored reaction mixturehad an acid number of 249 mg KOH/gram in pyridine/methanol. The highacid number indicated that the reaction mixture consisted predominantlyof a carboxyl-terminated unsaturated polyester. NMR spectroscopicanalysis revealed that the carbon-carbon double bonds in maleate form(cis) were isomerized to the fumarate form (trans) in thecarboxyl-terminated unsaturated polyester during the condensationreaction.

After the reaction mixture prepared above containing predominantly thecarboxyl-terminated unsaturated polyester was cooled to a temperature of120° C., 2.3 milliliters of fluoroboric acid (a 48 weight percentsolution in water) was added. Thereafter, for a period of 1 hour, 489grams (3.70 moles) of dicyclopentadiene were added slowly into thereaction flask with continuous rapid stirring at a temperature of from105° C. to 125° C. The reaction mixture was then maintained at atemperature of 120° C. for a period of 40 minutes with continuousstirring, and thereafter subjected to a vacuum of 27 inches of mercuryfor a period of 10 minutes. After the vacuum period, the reactionmixture was maintained at a temperature of 120° C. for an additional 10minute period with continuous stirring. The extent of the reactionbetween dicyclopentadiene and the carboxyl-terminated unsaturatedpolyester was monitored by titration for residual acid, and also by NMRspectroscopy.

Following the 10 minute heating period, 846 grams of styrene containing0.6 grams of methylhydroquinone were added into the reaction flask withcontinuous rapid stirring. The resulting mixture was a clear brownsolution containing a small amount of a solid by-product. This mixturewas stirred with 10 grams of Na₂ CO₃ and 10 grams of MgSO₄ for a periodof one hour. The resulting reaction mixture was then cooled to ambienttemperature and centrifuged to separate the supernatant liquid productfrom the solids. NMR spectroscopic analysis indicated that the solidby-product consisted predominantly of fumaric acid. The supernatantliquid product was a clear brown fluid with a viscosity of 78centipoises at 25° C. and having an acid number of 18 mg KOH/gram inpyridine/methanol. The low acid number indicated that the filtrateproduct consisted predominantly of the dicyclopentadiene-terminatedunsaturated polyester. NMR spectroscopic analysis indicated that theproduct prior to styrene addition consisted predominantly of adicyclopentadiene-terminated unsaturated polyester.

EXAMPLES 4 and 5

Into a 3 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added 980 grams (10.0moles) of molten maleic anhydride, 414 grams (6.67 moles) of ethyleneglycol and 100 milliliters of xylene. The resulting reaction mixture washeated to a temperature of 210° C. with continuous stirring over a 6hour period. At the end of the 6 hour period, 61 milliliters of waterhad been collected in the receiver. The reaction mixture was thenmaintained at a temperature of from 190° C. to 210° C. for a period of4.5 hours. The reaction mixture was then cooled to a temperature of 150°C., and thereafter subjected to a vacuum of about 27 inches of mercuryfor a period of 40 minutes to remove any residual water and xylene. Anitrogen blanket was maintained throughout the entire reaction period.As the reaction mixture was further cooled to ambient temperature, itformed a brittle solid. Titrimetric analysis indicated that theresulting reaction mixture had an acid number of 220 mg KOH/gram inpyridine/methanol. The high acid number indicated that the reactionmixture consisted predominantly of a carboxyl-terminated unsaturatedpolyester. NMR spectroscopic analysis revealed that the carbon-carbondouble bonds in maleate form (cis) were isomerized to the fumarate form(trans) in the carboxyl-terminated unsaturated polyester during thecondensation reaction.

To a 100 gram portion of the reaction mixture prepared above containingpredominantly the carboxyl-terminated unsaturated polyester, whichportion had been cooled to a temperature of 120° C., was added 0.03grams of methylhydroquinone and 0.5 milliliters of fluoroboric acid (a48 weight percent solution in water). Thereafter, for a period of about0.3 hours, an amount of dicyclopentadiene specified for each example inTable A was added slowly into the reaction flask with continuous rapidstirring at a temperature of from 105° C. to 118° C. The reactionmixture was then maintained at a temperature of 115° C. for a period ofone hour with continuous stirring. The extent of the reaction betweendicyclopentadiene and the carboxyl-terminated unsaturated polyester wasmonitored by titration for residual acid, and also by NMR spectroscopy.

Following the one hour heating period, an amount of styrene specifiedfor each example in Table A containing 0.05 grams of methylhydroquinonewas added into the reaction flask with continuous rapid stirring. Theresulting mixture was cooled to ambient temperature and filtered to givea filtrate product and a small amount of a solid by-product. NMRspectroscopic analysis indicated that the solid by-product consistedpredominantly of fumaric acid. The filtrate product was a clear brownfluid having a viscosity and an acid number specified for each examplein Table A. The low acid numbers indicated that the filtrate product foreach example consisted predominantly of the dicyclopentadiene-terminatedunsaturated polyester. NMR spectroscopic analysis indicated that theproduct for each example prior to styrene addition consistedpredominantly of the dicyclopentadiene-terminated unsaturated polyester.

                  TABLE A                                                         ______________________________________                                                            Example                                                                       4     5                                                   ______________________________________                                        Dicyclopentadiene Added (gms.)                                                                      51.8    57.0                                            Styrene Added (gms.)  101.2   104.6                                           Carboxyl-Terminated Unsaturated                                                                     1/1.00  1/1.10                                          Polyester/Dicyclopentadiene                                                   (mole ratio).sup.(a)                                                          Acid Number (mg KOH/gm)                                                                             43      27                                              ______________________________________                                         .sup.(a) Based on acid number determination.                             

EXAMPLE 6

Into a 5 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added 1569 grams (16.0moles) of molten maleic anhydride, 913 grams (12.0 moles) of propyleneglycol and 150 milliliters of xylene. The resulting reaction mixture washeated to a temperature of 190° C. with continuous stirring over a 3hour period. After 40 minutes into the 3 hour period, the reactionmixture had reached a temperature of 165° C. and the first drop ofdistillate (water) appeared in the receiver. At the end of the 3 hourperiod, the reaction mixture had reached a temperature of 190° C. and 72milliliters of water had been collected in the receiver. The reactionmixture was then maintained at a temperature of from 190° C. to 214° C.for a period of 8 hours. At the end of this 8 hour period, 130milliliters of water had been collected in the receiver. The reactionmixture was then cooled to a temperature of 150° C., and thereaftersubjected to a vacuum of about 27 inches of mercury for a period of 30minutes to remove any residual water and xylene. A nitrogen blanket wasmaintained throughout the entire reaction period. Titrimetric analysisindicated that the resulting yellow hazy reaction mixture had an acidnumber of 207 mg KOH/gram in pyridine/methanol. The high acid numberindicated that the reaction mixture consisted predominantly of acarboxyl-terminated unsaturated polyester. NMR spectroscopic analysisrevealed that the carbon-carbon double bonds in maleate form (cis) wereisomerized to the fumarate form (trans) in the carboxyl-terminatedunsaturated polyester during the condensation reaction.

To a 200 gram portion of the reaction mixture prepared above containingpredominantly the carboxyl-terminated unsaturated polyester, whichportion had been cooled to a temperature of 115° C., was added 0.089grams of methylhydroquinone and 0.6 milliliters of fluoroboric acid (a48 weight percent solution in water). Thereafter, for a period of 20minutes, 97.5 grams (0.74 moles) of resin grade dicyclopentadienecommercially available from Dow Chemical Company, Midland, Mich., as XAS1348, were added slowly into the reaction flask with continuous rapidstirring at a temperature of from 115° C. to 123° C. The reactionmixture was then maintained at a temperature of 115° C. for a period of45 minutes with continuous stirring, and thereafter subjected to avacuum of about 27 inches of mercury for a period of 20 minutes. Theextent of the reaction between dicyclopentadiene and thecarboxyl-terminated unsaturated polyester was monitored by titration forresidual acid, and also by NMR spectroscopy.

Following the 20 minute vacuum period, 241 grams of styrene containing0.09 grams of methylhydroquinone were added into the reaction flask withcontinuous rapid stirring. The resulting mixture was cooled to ambienttemperature and filtered to give a filtrate product and a small amountof a solid by-product. NMR spectroscopic analysis indicated that thesolid by-product consisted predominantly of fumaric acid. The filtrateproduct was a clear brown fluid with a viscosity of 52 centipoises at25° C. and an acid number of 40 mg KOH/gram in pyridine/methanol. Thelow acid number indicated that the filtrate product consistedpredominantly of the dicyclopentadiene-terminated unsaturated polyester.NMR spectroscopic analysis indicated that the product prior to styreneaddition consisted predominantly of a dicyclopentadiene-terminatedunsaturated polyester.

EXAMPLE 7

Into a 5 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added 1569 grams (16.0moles) of molten maleic anhydride, 913 grams (12.0 moles) of propyleneglycol and 150 milliliters of xylene. The resulting reaction mixture washeated to a temperature of 190° C. with continuous stirring over a 3hour period. After 40 minutes into the 3 hour period, the reactionmixture had reached a temperature of 165° C. and the first drop ofdistillate (water) appeared in the receiver. At the end of the 3 hourperiod, the reaction mixture had reached a temperature of 190° C. and 72milliliters of water had been collected in the receiver. The reactionmixture was then maintained at a temperature of from 190° C. to 214° C.for a period of 8 hours. At the end of this 8 hour period, 130milliliters of water had been collected in the receiver. The reactionmixture was then cooled to a temperaure of 150° C., and thereaftersubjected to a vacuum of about 27 inches of mercury for a period of 30minutes to remove any residual water and xylene. A nitrogen blanket wasmaintained throughout the entire reaction period. Titrimetric analysisindicated that the resulting yellow hazy reaction mixture had an acidnumber of 207 mg KOH/gram in pyridine/methanol. The high acid numberindicated that the reaction mixture consisted predominantly of acarboxyl-terminated unsaturated polyester. NMR spectroscopic analysisrevealed that the carbon-carbon double bonds in maleate form (cis) wereisomerized to the fumarate form (trans) in the carboxyl-terminatedunsaturated polyester during the condensation period.

To a 200 gram portion of the reaction mixture prepared above containingpredominantly the carboxyl-terminated unsaturated polyester, whichportion had been cooled to a temperature of 115° C., was added 0.09grams of methylhydroquinone and 10 milliliters of 2-hydroxyethylmethacrylate. After a period of 10 minutes, 0.6 milliliters offluoroboric acid (a 48 weight percent solution in water) were added intothe reaction flask. Thereafter, for a period of 20 minutes, 97.5 grams(0.74 moles) of dicyclopentadiene were added slowly into the reactionflask with continuous rapid stirring at a temperature of from 105° C. to125° C. The reaction mixture was then maintained at a temperature of115° C. for a period of 75 minutes with continuous stirring. The extentof the reaction between dicyclopentadiene and the carboxyl-terminatedunsaturated polyester was monitored by titration for residual acid, andalso by NMR spectroscopy.

Following the 75 minute heating period, 99.9 grams of styrene containing0.09 grams of methylhydroquinone were added into the reaction flask withcontinuous rapid stirring. The resulting mixture was cooled to ambienttemperature and filtered to give a filtrate product and a small amountof a solid by-product. NMR spectroscopic analysis indicated that thesolid by-product consisted predominantly of fumaric acid. The filtrateproduct was a clear brown fluid with a viscosity of 2260 centipoises at25° C. NMR spectroscopic analysis indicated that the product prior tostyrene addition consisted predominantly of adicyclopentadiene-terminated unsaturated polyester.

Comparative Example A describes the attempted preparation of adicyclopentadiene-terminated unsaturated polyester without the additionof a special acid catalyst.

COMPARATIVE EXAMPLE A

Into a 5 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added a 100 gram portionof the reaction mixture prepared in Example 7 above containingpredominantly the carboxyl-terminated unsaturated polyester, whichportion had been cooled to a temperature of 120° C., and 0.05 grams ofmethylhydroquinone. Thereafter, for a period of 0.3 hours, 48.7 grams(0.37 moles) of dicyclopentadiene were added slowly into the reactionflask with continuous rapid stirring at a temperature of from 105° C. to125° C. The reaction mixture was then maintained at a temperature of120° C. for a period of 5.5 hours with continuous stirring. The extentof the reaction between dicyclopentadiene and the carboxyl-terminatedunsaturated polyester was monitored by titration for residual acid, andalso by NMR spectroscopy. After 3.3 hours into the 5.5 hour heatingperiod, the reaction mixture was determined to have an acid number of130 mg KOH/gm in pyridine/methanol. At the end of the 5.5 hour heatingperiod, the reaction mixture was determined to have an acid number of129 mg KOH/gm in pyridine/methanol.

Following the 5.5 hour heating period, 99 grams of styrene containing0.025 grams of methylhydroquinone were added into the reaction flaskwith continuous rapid stirring. The resulting mixture was cooled toambient temperature and allowed to stand overnight. Upon observation thenext day, the reaction mixture consisted of two liquid layers and asolid precipitate. The top layer was primarily unreacteddicyclopentadiene and styrene, and the bottom layer was primarily theunreacted carboxyl-terminated unsaturated polyester. This reactionmixture was not suitable for use as a molding resin.

Examples 8 through 11 and Comparative Examples B through E show theeffect of choice of catalyst and amount thereof on the reaction of afumarate half ester, i.e., ethyl hydrogen fumarate, withdicyclopentadiene.

EXAMPLES 8 THROUGH 11 AND COMPARATIVE EXAMPLES B THROUGH E

Into a 25 mm×200 mm test tube having a magnetic stirring bar and sealedwith a serum cap was added 10.0 grams (0.069 moles) of ethyl hydrogenfumarate commercially available from the Aldrich Chemical Company,Milwaukee, Wis., and 9.16 grams (0.069 moles) of high puritydicyclopentadiene. After heating the reaction mixture to a temperatureof 120° C. with continuous stirring, an amount of a catalyst specifiedfor each example in Table B was added into the test tube. The resultingreaction mixture was maintained at a temperature of 120° C. for a periodof time specified for each example in Table B with continuous stirring.Samples were removed at time periods specified for each example in TableB and analyzed to determine the acid number thereof. The acid number isindicative of the extent of the reaction between ethyl hydrogen fumarateand dicyclopentadiene. The extent of the reaction is shown in Table B asthe percent decrease in acid number based on the acid number ofComparative Example A. Although equimolar amounts of the ethyl hydrogenfumarate and dicyclopentadiene were used, the acidity did not reach zerowhen all of the dicyclopentadiene had reacted since side reactionsconsumed a portion of the dicyclopentadiene.

                                      TABLE B                                     __________________________________________________________________________    Example/   Catalyst   Time                                                                             Acid Number                                                                           % Decrease                                   Comparative Example                                                                      (wt. %)    (hr.)                                                                            (mg KOH/gm)                                                                           in Acid Number                               __________________________________________________________________________    8          Fluoroboric Acid.sup.(a)                                                                 1.0                                                                              44      79                                                      (0.5)      3.0                                                                              44      79                                           9          Fluoroboric Acid.sup.(a)                                                                 1.0                                                                              161     23                                                      (0.1)      5.0                                                                              74      64                                           10         HPF.sub.6.sup.(b) (0.5)                                                                  1.0                                                                              92      56                                                                 4.0                                                                              50      76                                           11         Triflic Acid.sup.(e)                                                                     0.25                                                                             62      70                                                      (0.05)     2.0                                                                              58      72                                           B          None       0  209     0                                                                  2.0                                                                              208     0.5                                                                9.5                                                                              202     3                                            C          Sulfuric Acid                                                                            1.0                                                                              177     15                                                      (0.5)                                                              D          Concentrated Hydro-                                                                      1.0                                                                              209     0                                                       chloric Acid.sup.(c) (0.5)                                         E          CH.sub.3 SO.sub.3 H.sup.(d) (0.5)                                                        1.0                                                                              192     8                                            __________________________________________________________________________     .sup.(a) A 48 weight percent solution in water.                               .sup.(b) A 60 weight percent solution in water.                               .sup.(c) A 37 weight percent solution in water.                               .sup.(d) A 70 weight percent solution in water.                               .sup.(e) Trifluoromethanesulfonic acid.                                  

EXAMPLE 12

Into a 25 mm×200 mm test tube having a magnetic stirring bar and sealedwith a serum cap was added 5.72 grams (0.0397 moles) of ethyl hydrogenfumarate (commercially available from the Aldrich Chemical Company,Milwaukee, Wis.) and 3.63 grams (0.0394 moles) ofbicyclo[2.2.1]hepta-2,5-diene (commercially available from the AldrichChemical Company, Milwaukee, Wis.). After heating the reaction mixtureto a temperature of 120° C. with continuous stirring, 32 milliliters(0.5 weight percent) of fluoroboric acid (a 48 weight percent solutionin water) were added into the test tube. The resulting reaction mixturewas maintained at a temperature of 120° C. for a period of one hour withcontinuous stirring. The extent of the reaction between ethyl hydrogenfumarate and bicyclo[2.2.1]hepta-2,5-diene was monitored during thisperiod by titration for residual acid. A sample was removed from thetest tube after the one hour reaction period and analyzed to determinethe acid number thereof. Based on the initial acid number of thereaction mixture, an 86 percent decrease in acid number was observedafter the one hour reaction period.

EXAMPLE 13

Into a 25 mm×200 mm test tube having a magnetic stirring bar and sealedwith a serum cap was added 5.0 grams (0.0347 moles) of ethyl hydrogenfumarate (commercially available from the Aldrich Chemical Company,Milwaukee, Wis.) and 3.74 grams (0.40 moles) of bicyclo[2.2.1]-2-heptene(commercially available from the Aldrich Chemical Company, Milwaukee,Wis.). After heating the reaction mixture to a temperature of 120° C.with continuous stirring, 32 milliliters (0.5 weight percent) offluoroboric acid (a 48 weight percent solution in water) were added intothe test tube. The resulting reaction mixture was maintained at atemperature of 120° C. for a period of 3 hours with continuous stirring.The extent of the reaction between ethyl hydrogen fumarate and bicyclo[2.2.1]-2-heptene was monitored during this period by titration forresidual acid. A sample was removed from the test tube after the 3 hourreaction period and analyzed to determine the acid number thereof. Basedon the initial acid number of the reaction mixture, a 68 percentdecrease in acid number was observed after the 3 hour reaction period.

Examples 14 through 21 describe SPI gel time experiments using theprocedure described by A. L. Smith (6th SPI, Chicago, Ill., 1951,Reinforced Plastics Div., Section 1, page 1).

EXAMPLES 14 THROUGH 21

Into a small glass jar was added 20 grams of a resin specified for eachexample in Table C and 1 phr of benzoyl peroxide initiator. Theresulting mixture was stirred for 5 minutes and then poured into a 19mm×150 mm test tube to a depth of 3 inches. A thermocouple was placedinto the center of the mixture, and the test tube was then immersed inan oil bath at 82.3° C. The cure speed for each resin is reflected bythe gel time and by the total time to peak temperature. The gel time isthe time required for the temperature of the mixture to rise from 65.5°C. to 87.8° C. The total time is the time required for the temperatureof the mixture to rise from 65.5° C. to the peak temperature. The peaktemperature is the maximum temperature achieved during cure. The geltime, total time and peak temperature are given for each of the examplesin Table C. The styrene content of each resin is also given in Table C.The cured plug obtained from each of the examples was hard and clear.For some examples, additional monomer was added to produce thecompositions shown in Table C.

                                      TABLE C                                     __________________________________________________________________________                    Example                                                                       14  15  16  17  18  19  20  21                                __________________________________________________________________________    Resin Prepared from Example #                                                                 1   1   2   3   4   5   6   7                                 Styrene Content of Resin (wt. %)                                                              31.2                                                                              25..sup.(a)                                                                       45  40  40  40  40  25                                Gel Time (min.) 13.8                                                                              11.2                                                                              13.9                                                                              15.0                                                                              4.7 4.2 6.0 6.3                               Total Time (min.)                                                                             16.5                                                                              13.9                                                                              17.1                                                                              17.5                                                                              7.0 6.3 8.8 9.6                               Peak Temperature (°C.)                                                                 193 196 211 201 232 233 219 194                               __________________________________________________________________________     .sup.(a) Resin composition: 55 weight percent polyester, 25 weight percen     styrene, 20 weight percent hydroxyethyl methacrylate.                    

Examples 22 through 24 describe the preparation of unreinforced castingsfrom the resin compositions of this invention.

EXAMPLES 22 THROUGH 24

Into an 8 inch×8 inch×1/8 inch glass mold was poured a thermosettingresin mixture containing 140 grams of a resin specified for each examplein Table D, 0.7 grams of Zelec UN mold release which is anorganophosphate mold release agent commercially available from E. I.duPont de Nemours, Wilmington, Del., and 1.4 grams of t-butylperbenzoate initiator. The thermosetting resin mixture was then heatedusing a programmed temperature cycle, i.e., 16 hours at 65° C., 3 hoursat 85° C. and 4 hours at 125° C. The castings obtained from each of theexamples were hard and clear. The castings were tested for certainproperties identified in Table D and the results of such testing aregiven in Table D.

                  TABLE D                                                         ______________________________________                                                         Example                                                                       22    23        24                                           ______________________________________                                        Resin Prepared from Example #                                                                    2       3         7                                        Casting Properties                                                            Flexural Strength (10.sup.3 psi)                                                                 2.5     5.0       14.8                                     Flexural Modulus (10.sup.5 psi)                                                                  5.1     6.4       5.1                                      Heat Deflection Temperature (°C.)                                                         158     157       147                                      Barcol Hardness    45      44        45                                       ______________________________________                                    

Examples 25 through 28 describe the preparation of fiber reinforcedcomposites from the resin compositions of this invention.

EXAMPLES 25 THROUGH 28

Into a 10 inch×51/2 inch×1/10 inch constant volume mold preheated to atemperature specified for each example in Table E was injected athermosetting resin mixture containing a portion of the resin specifiedfor each example in Table E, an amount of Zelec UN mold release agentwhich is an organophosphate mold release commercially available from E.I. duPont de Nemours, Wilmington, Del., and an amount of t-butylperbenzoate initiator. The resin mixture employed in Example 26 alsocontained an amount of 2-hydroxyethyl methacrylate specified in Table E.Approximately 85 grams (5 plies) of AKM random glass mat commerciallyavailable from PPG Industries, Inc., Pittsburgh, Pa., was placed in the10 inch×51/2 inch×1/10 inch constant volume mold prior to injection. Themold was then closed and evacuated for about 5 seconds prior toinjection of the particular resin mixture. The injection time for eachof the examples is specified in Table E. An injection pressure of 250pounds per square inch was maintained for a dwell period of 5 secondsfor each example. The resin penetrated the glass web and wet the fibersbefore it formed a thermoset composition. Following the cure timespecified for each example, the resulting cured glass reinforcedcomposites were removed from the mold and tested for certain propertiesidentified in Table E. The results of such testing are given in Table E.

                  TABLE E                                                         ______________________________________                                                       Example                                                                       25    26      27      28                                       ______________________________________                                        Resin Mixture Composition                                                     Resin Prepared from                                                                            1       1       2     3                                      Example #                                                                     Resin (gms)      700.sup.(a)                                                                           800     600   500.sup.(c)                            Zelec UN Mold Release (gms)                                                                    3.5     5.0     3.0   3.0                                    t-Butyl Perbenzoate (gms)                                                                      10.5    15.0    9.0   9.0                                    2-Hydroxyethyl Methacrylate                                                                    --      200     --    --                                     (gms)                                                                         Molding Conditions                                                            Mold Temperature (°C.)                                                                  140     144     140   135                                    Injection Time (sec.)                                                                          4       7       7     14                                     Cure Time (sec.) 70      60      80    75                                     Total Mold Closed Time.sup.(b)                                                                 84      77      97    99                                     (sec.)                                                                        Composite Properties                                                          Tensile Strength (10.sup.3 psi)                                                                23.9    34.0    24.6  21.7                                   Tensile Modulus (10.sup.6 psi)                                                                 1.51    1.98    1.53  1.25                                   Elongation (%)   1.8     2.0     2.0   2.3                                    Flexural Strength (10.sup.3 psi)                                                               24.2    39.5    25.7  33.3                                   Flexural Modulus (10.sup.6 psi)                                                                1.20    2.05    1.49  1.70                                   Glass Content (wt. %)                                                                          54      62      54    52                                     ______________________________________                                         .sup.(a) 640 grams of the resin prepared from Example 1 was blended with      160 grams of styrene. A 700 gram portion of this mixture was used in the      preparation of a fiber reinforced composite.                                  .sup.(b) The total mold closed time includes the sum of the evacuation        time (5 seconds for each example), the injection time, the dwell time (5      seconds for each example) and the cure time.                                  .sup.(c) An additional 50 grams of styrene was added to this resin            mixture.                                                                 

As illustrated by Examples 25 through 28, fiber reinforced thermosetresin articles having high stiffness and strength can be produced fromthe curable resin compositions of this invention by a rapid injectionmolding process.

COMPARATIVE EXAMPLE F

Into a 3 liter four-necked round bottom reaction flask equipped with anitrogen inlet and outlet, paddle stirrer, electric heating mantle,thermometer with Therm-O-Watch controller and a 12 inch packeddistillation column and distillate receiver was added 588 grams (6.0moles) of molten maleic anhydride and 290 grams (4.68 moles) of ethyleneglycol. The resulting reaction mixture was heated to a temperature of90° C. over a one hour period with continuous stirring. When thetemperature reached 55° C., 75.6 milliliters (4.2 moles) of water wasadded to the reaction flask. The reaction mixture was maintained at atemperature of 90° C. for a period of one hour, after which 475 grams(3.6 moles) of resin grade dicyclopentadiene (commercially availablefrom Dow Chemical Company, Midland, Mich. as XAS 1348) was added to thereaction flask over a 12 minute period. The reaction mixture was thenheated to a temperature of 121° C. to 125° C. and maintained at thistemperature for a period of 3 hours. At the end of this period, thereaction mixture was further heated to a temperature of 200° C. over aperiod of one hour, and maintained at a temperature of 198° C. to 220°C. for a period of 8.5 hours as water was removed overhead. A nitrogenblanket was maintained throughout the entire reaction period. At the endof this period, the reaction mixture gelled. The product was unsuitablefor use as a resin.

COMPARATIVE EXAMPLE G

The procedure described in Comparative Example F was repeated with theexception that 0.5 milliliters of tributylphosphite was added to thereaction mixture. Tributylphosphite is a potential hydroperoxidedecomposer. This reaction mixture was heated to a temperature of 199° C.to 201° C. and maintained at this temperature for a period of 3.4 hours.At the end of this period, the reaction mixture gelled. The product wasunsuitable for use as a resin.

I claim:
 1. A process for preparing a resin composition comprising the steps of:(a) contacting a molar excess of an alpha, beta unsaturated dicarboxylic acid or derivative thereof with an organic polyol for a time and at a temperature sufficient to form a composition comprising a carboxylic acid terminated polyester having the formula: ##STR12## wherein n is a number having an average value of about 2 to less than about 4, m is a number equal to the free valence of R less the average value of n, the ratio of n to m is greater than about 2.0, and R is the residuum of a polyester which contained from 2 to 4 inclusive hydroxyl groups; (b) contacting a Diels-Alder adduct of cyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylated derivative thereof with the carboxylic acid terminated polyester of (a) in the presence of a non-oxidizing acid catalyst having a non-nucleophilic anion for a time and at a temperature sufficient to form a composition comprising an unsaturated ester having the formula: ##STR13## wherein n, m and R are as defined above and R₁ is the residuum of a Diels-Alder adduct of cyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylated derivative thereof having from 2 to about 20 carbon atoms; and (c) admixing a copolymerizable ethylenically unsaturated monomer with the unsaturated ester of (b).
 2. A process as defined in claim 1 wherein the alpha, beta unsaturated dicarboxylic acid or derivative thereof in step (a) is selected from maleic acid or anhydride and fumaric acid.
 3. A process as defined in claim 1 wherein the alpha, beta unsaturated dicarboxylic acid or derivative thereof in step (a) is present in a molar excess amount of between 5 and 60 percent.
 4. A process as defined in claim 1 wherein the organic polyol in step (a) is selected from ethylene glycol, diethylene glycol, propylene glycol, trimethylol propane, polycaprolactone esters of trimethylol propane or 1,4-butanediol, 2,2-bis(4-hydroxyphenyl) propane, and the ethylene and propylene oxide adducts of 2,2-bis(4-hydroxyphenyl) propane.
 5. A process as defined in claim 1 wherein step (a) is carried out at a temperature of from 170° C. to 220° C.
 6. A process as defined in claim 1 wherein the carboxylic acid terminated polyester of formula (I) and the unsaturated ester of formula (II) have a ratio of n to m of at least about 3.0.
 7. A process as defined in claim 1 wherein step (b) is carried out at a temperature of from 80° C. to 140° C.
 8. A process of defined in claim 1 wherein the Diels-Alder adduct of cyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylated derivative thereof in step (b) is selected from dicyclopentadiene, norbornene and norbornadiene.
 9. A process as defined in claim 1 wherein the Diels-Alder adduct of cyclopentadiene with an olefinic or acetylenic hydrocarbon or alkylated derivative thereof in step (b) is dicyclopentadiene.
 10. A process as defined in claim 1 wherein the non-oxidizing acid catalyst having a non-nucleophilic anion in step (b) is selected from fluoroboric acid, hexafluorophosphoric acid, hexafluoroantimonic acid and trifluoromethanesulfonic acid (triflic acid).
 11. A process as defined in claim 1 wherein the non-oxidizing acid catalyst having a non-nucleophilic anion in step (b) is fluoroboric acid.
 12. A process as defined in claim 1 wherein the non-oxidizing acid catalyst having a non-nucleophilic anion in step (b) is present in an amount of from 0.01 weight percent to 4.0 weight percent based on the weight of the unsaturated ester of step (b).
 13. A process as defined in claim 1 wherein the copolymerizable ethylenically unsaturated monomer in step (c) is styrene.
 14. A process as defined in claim 1 wherein the copolymerizable ethylenically unsaturated monomer in step (c) is a mixture of styrene and 2-hydroxyethyl methacrylate.
 15. A process as defined in claim 1 wherein the copolymerizable ethylenically unsaturated monomer in step (c) is present in an amount of from 10 weight percent to 75 weight percent based on the weight of the resin composition.
 16. A process as defined in claim 1 further comprising treating the resin composition with a weak base.
 17. A process as defined in claim 16 wherein the weak base is selected from crosslinked polyvinylpyridine, disodium acid phosphate, sodium carbonate and alumina.
 18. A resin composition prepared according to the process of claim
 1. 19. A cured molded article prepared from the resin composition of claim
 18. 20. A cured molded article prepared from the resin composition of claim 18 wherein the molded article contains one or more fibers with a melting point or a glass transition temperature above about 130° C. 